text: The dihelium excimer is an important component in the helium discharge lamp.
  A second use of dihelium ion is in ambient ionization techniques using low temperature plasma. In this helium atoms are excited, and then combine to yield the dihelium ion. The He goes on to react with N in the air to make N.  These ions react with a sample surface to make positive ions that are used in mass spectroscopy. The plasma containing the helium dimer can be as low as 30 °C in temperature, and this reduces heat damage to samples.